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Abstract

The perceptual appearance of a visual stimulus can be changed by presenting stimuli that are similar, but that differ along specific dimensions, to the observer in advance. Many negative adaptation aftereffects are familiar to students of perception, for example. A different example is “cue recruitment” (Haijiang et al., 2006): a visual signal that has no effect on some attribute of appearance can often be made to affect that attribute through the use of classical (Pavlovian) conditioning procedures. In that case, the signal has come to be treated as a new cue by the visual system, insofar as it now participates in the construction of some new aspect of appearance that it previously did not. We asked whether this learning requires that the signal be visible, i.e. whether it must have a consciously accessible perceptual consequence, of any sort, during training. To do this we employed an invisible visual signal, namely, a vertical gradient of vertical disparity obtained by slightly magnifying the image in one eye. This signal is measured by the visual system, but it had no influence on any of the perceptual attributes that observers’ visual systems computed from the displays, in which horizontal lines depicted a rotating cylinder. During training we made the eye of vertical magnification (EVM) contingent on the rotation direction of the cylinder. After training we presented an ambiguous version of the cylinder and found that EVM influenced the perceived direction of rotation consistent with contingency during training. Thus, a signal need not be visible for the adult visual system to give it new use as a participant in the construction of visual appearances. Haijiang, Q., Saunders, J. A., Stone, R. W., Backus, B. T. (2006). Demonstration of cue recruitment: Change in visual appearance by means of Pavlovian conditioning. PNAS, 103, 483–486.